pgsql: Avoid useless buffer allocations during binary COPY FROM.

Avoid useless buffer allocations during binary COPY FROM.

The raw_buf and line_buf buffers aren't used when reading binary format,
so skip allocating them.  raw_buf is 64K so that seems like a worthwhile
savings.  An unused line_buf only wastes 1K, but as long as we're checking
it's free to avoid allocating that too.

Bharath Rupireddy, tweaked a bit by me

Discussion: https://postgr.es/m/CALj2ACXcCKaGPY0whowqrJ4OPJvDnTssgpGCzvuFQu5z0CXb-g@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cd22d3cdb9bd9963c694c01a8c0232bbae3ddcfb

Modified Files
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src/backend/commands/copy.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)